/*
 *    Copyright 2009-2013 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.binding;

import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.session.SqlSession;

import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.util.*;

/**
 * @author Clinton Begin
 * @author Eduardo Macarron
 * @author Lasse Voss
 */
public class MapperMethod {

	private final SqlCommand command;
	private final MethodSignature method;

	public MapperMethod(Class<?> mapperInterface, Method method, Configuration config) {
		this.command = new SqlCommand(config, mapperInterface, method);
		this.method = new MethodSignature(config, method);
	}

	public Object execute(SqlSession sqlSession, Object[] args) {
		Object result;
		if (SqlCommandType.INSERT == command.getType()) {
			Object param = method.convertArgsToSqlCommandParam(args);
			result = rowCountResult(sqlSession.insert(command.getName(), param));
		} else if (SqlCommandType.UPDATE == command.getType()) {
			Object param = method.convertArgsToSqlCommandParam(args);
			result = rowCountResult(sqlSession.update(command.getName(), param));
		} else if (SqlCommandType.DELETE == command.getType()) {
			Object param = method.convertArgsToSqlCommandParam(args);
			result = rowCountResult(sqlSession.delete(command.getName(), param));
		} else if (SqlCommandType.SELECT == command.getType()) {
			if (method.returnsVoid() && method.hasResultHandler()) {
				executeWithResultHandler(sqlSession, args);
				result = null;
			} else if (method.returnsMany()) {
				result = executeForMany(sqlSession, args);
			} else if (method.returnsMap()) {
				result = executeForMap(sqlSession, args);
			} else {
				Object param = method.convertArgsToSqlCommandParam(args);
				result = sqlSession.selectOne(command.getName(), param);
			}
		} else {
			throw new BindingException("Unknown execution method for: " + command.getName());
		}
		if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {
			throw new BindingException("Mapper method '" + command.getName() + " attempted to return null from a method with a primitive return type (" + method.getReturnType()
					+ ").");
		}
		return result;
	}

	private Object rowCountResult(int rowCount) {
		final Object result;
		if (method.returnsVoid()) {
			result = null;
		} else if (Integer.class.equals(method.getReturnType()) || Integer.TYPE.equals(method.getReturnType())) {
			result = rowCount;
		} else if (Long.class.equals(method.getReturnType()) || Long.TYPE.equals(method.getReturnType())) {
			result = (long) rowCount;
		} else if (Boolean.class.equals(method.getReturnType()) || Boolean.TYPE.equals(method.getReturnType())) {
			result = (rowCount > 0);
		} else {
			throw new BindingException("Mapper method '" + command.getName() + "' has an unsupported return type: " + method.getReturnType());
		}
		return result;
	}

	private void executeWithResultHandler(SqlSession sqlSession, Object[] args) {
		MappedStatement ms = sqlSession.getConfiguration().getMappedStatement(command.getName());
		if (void.class.equals(ms.getResultMaps().get(0).getType())) {
			throw new BindingException("method " + command.getName() + " needs either a @ResultMap annotation, a @ResultType annotation,"
					+ " or a resultType attribute in XML so a ResultHandler can be used as a parameter.");
		}
		Object param = method.convertArgsToSqlCommandParam(args);
		if (method.hasRowBounds()) {
			RowBounds rowBounds = method.extractRowBounds(args);
			sqlSession.select(command.getName(), param, rowBounds, method.extractResultHandler(args));
		} else {
			sqlSession.select(command.getName(), param, method.extractResultHandler(args));
		}
	}

	private <E> Object executeForMany(SqlSession sqlSession, Object[] args) {
		List<E> result;
		Object param = method.convertArgsToSqlCommandParam(args);
		if (method.hasRowBounds()) {
			RowBounds rowBounds = method.extractRowBounds(args);
			result = sqlSession.<E> selectList(command.getName(), param, rowBounds);
		} else {
			result = sqlSession.<E> selectList(command.getName(), param);
		}
		// issue #510 Collections & arrays support
		if (!method.getReturnType().isAssignableFrom(result.getClass())) {
			if (method.getReturnType().isArray()) {
				return convertToArray(result);
			} else {
				return convertToDeclaredCollection(sqlSession.getConfiguration(), result);
			}
		}
		return result;
	}

	private <E> Object convertToDeclaredCollection(Configuration config, List<E> list) {
		Object collection = config.getObjectFactory().create(method.getReturnType());
		MetaObject metaObject = config.newMetaObject(collection);
		metaObject.addAll(list);
		return collection;
	}

	@SuppressWarnings("unchecked")
	private <E> E[] convertToArray(List<E> list) {
		E[] array = (E[]) Array.newInstance(method.getReturnType().getComponentType(), list.size());
		array = list.toArray(array);
		return array;
	}

	private <K, V> Map<K, V> executeForMap(SqlSession sqlSession, Object[] args) {
		Map<K, V> result;
		Object param = method.convertArgsToSqlCommandParam(args);
		if (method.hasRowBounds()) {
			RowBounds rowBounds = method.extractRowBounds(args);
			result = sqlSession.<K, V> selectMap(command.getName(), param, method.getMapKey(), rowBounds);
		} else {
			result = sqlSession.<K, V> selectMap(command.getName(), param, method.getMapKey());
		}
		return result;
	}

	public static class ParamMap<V> extends HashMap<String, V> {

		private static final long serialVersionUID = -2212268410512043556L;

		@Override
		public V get(Object key) {
			if (!super.containsKey(key)) {
				throw new BindingException("Parameter '" + key + "' not found. Available parameters are " + keySet());
			}
			return super.get(key);
		}

	}

	public static class SqlCommand {

		private final String name;
		private final SqlCommandType type;

		public SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method) throws BindingException {
			String statementName = mapperInterface.getName() + "." + method.getName();
			MappedStatement ms = null;
			if (configuration.hasStatement(statementName)) {
				ms = configuration.getMappedStatement(statementName);
			} else if (!mapperInterface.equals(method.getDeclaringClass().getName())) { // issue
																						// #35
				String parentStatementName = method.getDeclaringClass().getName() + "." + method.getName();
				if (configuration.hasStatement(parentStatementName)) {
					ms = configuration.getMappedStatement(parentStatementName);
				}
			}
			if (ms == null) {
				throw new BindingException("Invalid bound statement (not found): " + statementName);
			}
			name = ms.getId();
			type = ms.getSqlCommandType();
			if (type == SqlCommandType.UNKNOWN) {
				throw new BindingException("Unknown execution method for: " + name);
			}
		}

		public String getName() {
			return name;
		}

		public SqlCommandType getType() {
			return type;
		}
	}

	public static class MethodSignature {

		private final boolean returnsMany;
		private final boolean returnsMap;
		private final boolean returnsVoid;
		private final Class<?> returnType;
		private final String mapKey;
		private final Integer resultHandlerIndex;
		private final Integer rowBoundsIndex;
		private final SortedMap<Integer, String> params;
		private final boolean hasNamedParameters;

		public MethodSignature(Configuration configuration, Method method) throws BindingException {
			this.returnType = method.getReturnType();
			this.returnsVoid = void.class.equals(this.returnType);
			this.returnsMany = (configuration.getObjectFactory().isCollection(this.returnType) || this.returnType.isArray());
			this.mapKey = getMapKey(method);
			this.returnsMap = (this.mapKey != null);
			this.hasNamedParameters = hasNamedParams(method);
			this.rowBoundsIndex = getUniqueParamIndex(method, RowBounds.class);
			this.resultHandlerIndex = getUniqueParamIndex(method, ResultHandler.class);
			this.params = Collections.unmodifiableSortedMap(getParams(method, this.hasNamedParameters));
		}

		public Object convertArgsToSqlCommandParam(Object[] args) {
			final int paramCount = params.size();
			if (args == null || paramCount == 0) {
				return null;
			} else if (!hasNamedParameters && paramCount == 1) {
				return args[params.keySet().iterator().next()];
			} else {
				final Map<String, Object> param = new ParamMap<Object>();
				int i = 0;
				for (Map.Entry<Integer, String> entry : params.entrySet()) {
					param.put(entry.getValue(), args[entry.getKey()]);
					// issue #71, add param names as param1, param2...but ensure
					// backward compatibility
					final String genericParamName = "param" + String.valueOf(i + 1);
					if (!param.containsKey(genericParamName)) {
						param.put(genericParamName, args[entry.getKey()]);
					}
					i++;
				}
				return param;
			}
		}

		public boolean hasRowBounds() {
			return (rowBoundsIndex != null);
		}

		public RowBounds extractRowBounds(Object[] args) {
			return (hasRowBounds() ? (RowBounds) args[rowBoundsIndex] : null);
		}

		public boolean hasResultHandler() {
			return (resultHandlerIndex != null);
		}

		public ResultHandler extractResultHandler(Object[] args) {
			return (hasResultHandler() ? (ResultHandler) args[resultHandlerIndex] : null);
		}

		public String getMapKey() {
			return mapKey;
		}

		public Class<?> getReturnType() {
			return returnType;
		}

		public boolean returnsMany() {
			return returnsMany;
		}

		public boolean returnsMap() {
			return returnsMap;
		}

		public boolean returnsVoid() {
			return returnsVoid;
		}

		private Integer getUniqueParamIndex(Method method, Class<?> paramType) {
			Integer index = null;
			final Class<?>[] argTypes = method.getParameterTypes();
			for (int i = 0; i < argTypes.length; i++) {
				if (paramType.isAssignableFrom(argTypes[i])) {
					if (index == null) {
						index = i;
					} else {
						throw new BindingException(method.getName() + " cannot have multiple " + paramType.getSimpleName() + " parameters");
					}
				}
			}
			return index;
		}

		private String getMapKey(Method method) {
			String mapKey = null;
			if (Map.class.isAssignableFrom(method.getReturnType())) {
				final MapKey mapKeyAnnotation = method.getAnnotation(MapKey.class);
				if (mapKeyAnnotation != null) {
					mapKey = mapKeyAnnotation.value();
				}
			}
			return mapKey;
		}

		private SortedMap<Integer, String> getParams(Method method, boolean hasNamedParameters) {
			final SortedMap<Integer, String> params = new TreeMap<Integer, String>();
			final Class<?>[] argTypes = method.getParameterTypes();
			for (int i = 0; i < argTypes.length; i++) {
				if (!RowBounds.class.isAssignableFrom(argTypes[i]) && !ResultHandler.class.isAssignableFrom(argTypes[i])) {
					String paramName = String.valueOf(params.size());
					if (hasNamedParameters) {
						paramName = getParamNameFromAnnotation(method, i, paramName);
					}
					params.put(i, paramName);
				}
			}
			return params;
		}

		private String getParamNameFromAnnotation(Method method, int i, String paramName) {
			final Object[] paramAnnos = method.getParameterAnnotations()[i];
			for (Object paramAnno : paramAnnos) {
				if (paramAnno instanceof Param) {
					paramName = ((Param) paramAnno).value();
				}
			}
			return paramName;
		}

		private boolean hasNamedParams(Method method) {
			boolean hasNamedParams = false;
			final Object[][] paramAnnos = method.getParameterAnnotations();
			for (Object[] paramAnno : paramAnnos) {
				for (Object aParamAnno : paramAnno) {
					if (aParamAnno instanceof Param) {
						hasNamedParams = true;
						break;
					}
				}
			}
			return hasNamedParams;
		}

	}

}
